Engineering interfacial charge transfer is essential for improving the photocatalytic performance of semiconductor heterostructures. Herein, an inverse-opal g-C3N4 (SCN)-supported Bi-based heterostructure composed of Bi2WO6, Bi2SiO5 and BiOClxBr1-x was fabricated via a halogen-regulated interfacial assembly strategy. The three-dimensional SCN scaffold provides a porous architecture with enhanced light harvesting and abundant accessible sites for the growth of Bi-based phases, thereby facilitating intimate multi-interface coupling. Meanwhile, Cl/Br incorporation modulates the local electronic structure of the Bi-containing components and is expected to favor interfacial charge redistribution, thereby improving carrier separation and visible-light utilization. The optimized composite shows enhanced photocatalytic performance under simulated sunlight toward the removal of antibiotic contaminants, including norfloxacin, ciprofloxacin, and tetracycline; Rh B degradation was also examined as a comparative probe of photocatalytic activity. Based on radical-scavenging tests, band-structure analysis, photoluminescence measurements, electrochemical impedance spectroscopy, and transient photocurrent responses, an S-scheme-like charge-transfer pathway is tentatively proposed. This interfacial process is expected to preserve the redox capability of photogenerated carriers, thereby accelerating oxygen activation and pollutant oxidation. Overall, this study demonstrates that integrating an inverse-opal carbon nitride scaffold with halogen-regulated Bi-based heterostructures is an effective strategy for constructing photocatalysts with improved interfacial dynamics and practical potential for antibiotic remediation under simulated sunlight.